The present invention generally relates to the field of wireless telecommunications devices, and more specifically to systems for reducing power consumption in wireless telecommunications devices, thereby extending battery life and improving overall system performance.
As is known, wireless telecommunications devices typically derive their operating power from a battery. The larger the battery, i.e., the greater the battery capacity, the longer the wireless telecommunications device is able to operate without requiring replacement or recharging of the depleted battery. Given size and weight restrictions, the designer of the wireless device is under extreme pressure to use the minimum sized battery that will provide a reasonable amount of use between battery replacement or recharge. With the size of a battery generally being fixed by external factors, the designer must devote more time and money to increasing the amount of time that the wireless telecommunications device can operate using the chosen battery, i.e., increasing the battery life. Increased battery life (resulting from lowering the power consumption requirements of a device) allows for greater talk times, longer stand by times, and permits the use of smaller and less expensive batteries.
Typically, there are many different methods for increasing battery life. These range from using different and perhaps more efficient circuit components that use less battery current when operating, decreasing the total number of components used, integrating multiple discreet components into a single integrated circuit, etc. However, once a circuit design has been finalized, there are only a few ways to increase battery life. One known method used to increase battery life in a digital circuit is to implement a sleep function in the circuitry. Typically, a sleep function will either power down the entire circuit or power down certain non-critical portions of the circuit when the wireless communications device is not in active use. During sleep mode, the wireless communications device must retain the ability to receive incoming calls from other users and control commands from the controlling base stations, so the wireless communications device cannot be placed into a total power down mode, i.e., the phone cannot be turned off. Also, many wireless communications devices must retain a timing reference which is accurate with respect to the system time in order to prevent the wireless communications device from losing synchronization with the system.
In the Code Division Multiple Access (CDMA) standard, as specified by the TIA/EIA/IS-95A xe2x80x9cMobile Station-Base Station Compatibility Standard for Dual-Mode Wideband Spread Spectrum Cellular System,xe2x80x9d a CDMA subscriber unit (the wireless communications device) is assigned a certain time slot, where its communications are placed. Any CDMA device that is placed in a power down, or sleep, mode must nevertheless retain the ability to monitor its assigned slot. If the CDMA subscriber unit cannot do this, then it is not allowed to power down. When a CDMA subscriber unit is operating in this fashion, it is referred to as operating in slotted mode. Additionally, in the TIA/EIA/IS-95A standard, there are provisions for the controlling base station to command a subscriber unit to scan extra CDMA frequencies for potential connection hand-off base stations (e.g., when traveling from zone to zone). This is known as a scanning mode. As with the slotted mode, it is important for CDMA subscriber units to monitor commands that are received from base stations, such as those instructing the units of new pilot channels (e.g., connection hand-offs).
The present invention is generally directed to a system for improving the battery life in a wireless communications device by placing certain portions of the wireless communications device in either a low power state or shutting down power to these portions entirely, where the specific portions of the wireless communications device which are placed into the low power state or shut down depends on the current operating mode of the wireless communications device. In accordance with one aspect of the present invention, a method is provided for operating a wireless communications device in a low power mode, including a step of controlling the operation of circuit components to operate in either a low-power standby mode or an operating mode. The method detects a first condition and, in response to the detection of the first condition, operates a first set of circuit components in a low-power standby mode while operating a second set of circuit components in the operating mode. The method further includes the steps of detecting a second condition and, in response to the detection of the second condition, operating substantially all the circuit components in the full power operating mode.
In a preferred embodiment, the method further includes the steps of detecting a third condition and, in response to the detection of the third condition, operating a third set of circuit components in a low-power standby mode while operating a fourth set of circuit components in the operating mode. The first condition is the recognition of operation of the wireless device in a slotted mode of operation, when the device is communicating in accordance with a Code Division Multiple Access (CDMA) standard. The first set of circuit components preferably includes a pilot channel searching component, at least one data demodulating component, an automatic gain controller unit, an arithmetic unit, and a combiner unit, or any subset of components thereof.
The second condition is the recognition of operation of the wireless device in a scanning mode of operation when the device is communicating in accordance with a CDMA standard. The third set of circuit components preferably includes at least one data demodulating component, an automatic gain controller unit, an arithmetic unit, and a combiner unit, or any subset of components thereof. The fourth set of circuit components preferably includes a pilot channel searching component, an arithmetic unit, a plurality of registers, and a state machine that is configured to control the operation of the circuit components, or any subset of components thereof.
According to a preferred embodiment of the present invention, and depending on the functional and power requirements of the current operating mode of the wireless communications device, all power may be removed, or normal power may be applied, to each specific portion of the circuitry in the wireless communications device. Therefore, the present invention provides a system for reducing the power usage of a wireless communications device by powering down or turning off select portions of the device (depending on the present mode of operation) which are not needed. The invention further provides a system where, depending on the specific functional requirements of the wireless communications device, the circuitry in the wireless communications device may be specifically turned on or off.
Objects, features, and advantages of the present invention will become apparent upon reading and understanding the present specifications, when taken in conjunction with accompanying drawings.